| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a program method for a multi-level non-volatile memory device. <P>SOLUTION: The program method by the multi-level non-volatile memory providing flag cells of at least one or more and a plurality of multi-bit preserving cells includes: a step for programming the highest bit after the least significant bit is programmed previously in the preserving cell so as to have the threshold value being lower than VR1 when magnitude of reference voltage is VR1<VR2<VR3 and the first value is preserved in the preserving cell, to have the threshold voltage being higher than VR1 and lower than VR2 when the second value is preserved in the preserving cell, to have the threshold voltage being higher than than VR2 and lower than VR3 when the third value is preserved in the preserving cell, and to have the threshold voltage being higher than than VR3 when the fourth value is preserved in the preserving cell; and a step for programming the flag cell so as to have the threshold voltage being higher than VR3 to indicate that the highest order bit is programmed. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
